Microstructure and Weibull distribution of rupture strength of clay-talc ceramics

Abstract The mechanical properties of clay-talc ceramics containing 0 to 10 wt% of talc fired at 1100 °C were obtained by flexural measurements. With the average value of flexural strength of 23.1 MPa, the sample with 5 wt% of talc (G5) was the strongest and it had the lowest value of interconnected pore (64%). The scattering of strength values was described with the Weibull distribution model. For all samples, Weibull plots showed either a typical linear behavior or a multi-stage response and the Weibull modulus varied in a large range of 3 to 14, depending on the ceramic type and on the applied load. Interconnections between pores formed a network of possible failures under the stress field, resulting in a change of Weibull plots. Reducing the grain size range and the pore interconnectivity led to a reduced strength distribution. The flaw size range had a unimodal distribution for sample G5 with homogeneous microstructure and correspondingly a Weibull modulus m=9.79.